title: Characterization of retrotransposon sequences expressed in inflorescences of apomictic and sexual Paspalum notatum plants.
abstract: Apomixis, an asexual mode of reproduction through seeds, holds much promise for agricultural advances. However, the molecular mechanisms underlying this trait are still poorly understood. We previously isolated several transcripts representing novel sequences differentially expressed in reproductive tissues of sexual and apomictic plants. Here, we report the characterization of two of these unknown RNA transcripts (experimental codes N17 and N22). Since original fragments showed no significant homologies to sequences at databases, preliminary genomic PCR experiments were carried out to discard possible contaminations. RACE extension on flanking regions provided longer sequences for the candidates and additional related transcripts, which revealed similarity to LTR retrotransposons carrying short transduplicated segments of protein-coding genes. Interestingly, some transduplicated segments corresponded to genes previously associated with apomictic development. Gene copy number estimations revealed a moderate representation of the elements in the genome, with significantly increased numbers in a sexual genotype with respect to an apomictic one. Genetic mapping of N17 showed that a copy of this particular element was located onto Paspalum notatum linkage group F3c, at a central non-recombinant region resembling a centromere. Expression analysis showed an increased activity of N17 and N22 sense strands in ovules of the sexual genotypes. A retrotransposon-specific differential display analysis aimed at detecting related sequences allowed the identification of a complex family, with the majority of its members represented in the sexual genotype. Our results suggest that these elements could be participating in regulatory pathways related to apomixis and sexuality.
authors.affiliation: Laboratorio Central de Investigaciones, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Parque Villarino, S2125ZAA, Zavalla, Santa Fe, Argentina.
authors.forename: Ana Claudia
authors.initials: AC
authors.lastname: Ochogavía
authors.forename: José Guillermo
authors.initials: JG
authors.lastname: Seijo
authors.forename: Ana María
authors.initials: AM
authors.lastname: González
authors.forename: Maricel
authors.initials: M
authors.lastname: Podio
authors.forename: Erica
authors.initials: E
authors.lastname: Duarte Silveira
authors.forename: Ana Luiza
authors.initials: AL
authors.lastname: Machado Lacerda
authors.forename: Vera
authors.initials: V
authors.lastname: Tavares de Campos Carneiro
authors.forename: Juan Pablo A
authors.initials: JP
authors.lastname: Ortiz
authors.forename: Silvina Claudia
authors.initials: SC
authors.lastname: Pessino
mesh_terms: D002874:Chromosome Mapping; D035263:Flowering Tops / Q000378:metabolism*; D018628:Gene Dosage; D018745:Genome, Plant; D017403:In Situ Hybridization; D021141:Nucleic Acid Amplification Techniques; D031781:Paspalum / Q000235:genetics / Q000378:metabolism*; D012100:Reproduction, Asexual; D018626:Retroelements
chemical_list: D018626:Retroelements